Vitamin A in Protection from Sunlight.

β-Carotene and other carotenoids in protection from sunlight.

Abstract

Protectionagainst skin damage fromsunlightby nutritional means has been examined. Likewise, there has been work on the topical application of phytochemicals to the skin. This review focuses on the nutritional aspect of phytochemicals in humans-ie, the provision of carotenoid micronutrients by dietary means to the skin and their role inprotection. Human intervention studies have documented protective effects for β-caroteneor for lycopene provided either by a carotenoid-rich diet or by supplementation. In exposed tissues, light induces primary and secondary photooxidative processes. Scavenging of reactive oxygen species is considered to be a mechanism of action underlying the protective activity ofcarotenoids. However, food comprises a complex mixture of numerous constituents, so thatothercomponents may also contribute to the observed activity. Molecules with suitable structures absorb UV light and prevent direct damage of cellular targets. Phytoene and phytofluene are precursor molecules of higher unsaturatedcarotenoidsand occur in various fruit and vegetables. Their absorption spectra cover the UVB and UVA range, respectively, thus potentially contributing to photoprotective effects of carotenoid-rich food. Because of the physiologic turnover time of skin, several weeks are required for protective effects to appear. Photoprotection through individual dietary components such as β-caroteneor lycopene in terms of sunprotectionfactor is considerably lower than that achieved by using topical sunscreens. However, an optimal supply of antioxidant micronutrients in the skin increases basal dermal defense against UV irradiation, supports longer-termprotection, and contributes to maintenance of skin health and appearance.